They exist. They bear the mark of the devil inside them. They may be your neighbors. They may be your wife, husband, sweetheart. They may even be your children. Their time has come.

Jane lives in London with her boyfriend Richard. Her mother was murdered when she was young, she recently lost a baby in a car crash and she's plagued by nightmares of a knife-wielding man. Richard thinks that the cure is vitamins, while Jane's sister recommends psychiatric help. But a new neighbour promises that if she participates in a Black Mass, all her fears will disappear, instead it just seems to bring her nightmares to life.